Last updated 
Other operators
where
  pact
(where field f obj)  pact
(where field f obj)- takes 
field:string - takes 
f: a ->bool - takes 
obj:object - produces 
bool 
utility for use in filter and select applying f to field in obj
Supported in either invariants or properties.
typeof
  pact
(typeof a)  pact
(typeof a)- takes 
a: a - produces 
string 
return the type of a as a string
Supported in either invariants or properties.